TRACER-MAP

TRACER-MAP: Mapping Aerosol across Houston

1 July 2022 - 31 August 2022

Lead Scientist: Rebecca Sheesley

Observatory: AMF (ARM Mobile Facility 1) - HOU

Introduction. Thunderstorms and precipitation can be affected by small aerosol particles emitted and produced by urban and industrial pollution sources. There is still a lot that scientists do not understand about these interactions and how important urban pollution is in convective storm initiation and activity (convection is the broad term that describes the vertical motion that initiates thunderstorms). The Houston, TX Metropolitan area was selected for the 2021 Tracking Aerosol Convection Interactions Experiment (TRACER) due to its high convective storm activity and broad range of polluted aerosol conditions. With the overall TRACER project in mind, we planned TRACER-MAP, a related investigation of the impacts of convective storms on atmospheric composition, chemistry and aerosol processing in Houston. Because the Houston metroplex is large and has a wide range of atmospheric conditions, this project will “MAP” the air chemistry conditions across Houston while atmospheric scientists working in the TRACER project monitor convective storm activity overhead. Specifically, we will conduct a series of aerosol, gas, and meteorological measurements in the summer of 2021 that will match measurements from the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Mobile Facilities. Methods. We will locate our instruments and make measurements at established air monitoring sites across Houston so that we can compare with previous studies and have good spatial coverage in the metroplex. Specifically, we will deploy our Mobile Air Quality Laboratory 2 (MAQL2) to conduct particle size, distribution and detailed composition, cloud condensation nuclei (CCN) concentration and activity, aerosol optical properties, gas and meteorology measurements at multiple sites across Houston. These detailed atmospheric chemistry measurements will be integrated with atmospheric modeling to evaluate how observed differences across Houston are related to emissions, aerosol processes and convective storm activity. Project Objectives

1. Conduct aerosol (particle size, distribution and composition, CCN concentration and activity, aerosol optical properties), gas and meteorology measurements at satellite sites across Houston to complement and enhance measurements by the DOE during the TRACER campaign and make campaign data available to the TRACER scientific community to complement and enhance future modeling efforts.
2. Determine spatial variability across the Houston metropolitan area of aerosol characteristics in pre- and post-storm scenarios in terms of particle size, distribution, composition, CCN activity and optical properties.
3. Determine how urban aerosol processing differs between pre- and post-storm atmospheres in terms of particle growth, aging and CCN activity utilizing integration of observations and modeling.
4. Identify potential influences of convective transport (e.g. downdrafts) on particle size, number and composition through the interpretation of in situ and airborne chemical measurements.

Outcomes and Benefits. The TRACER-MAP datasets will provide key aerosol, gas and atmospheric measurements to assess the spatial heterogeneity of aerosol regimes across Houston, which can be utilized to answer science questions in the current project and by future DOE projects. The datasets will be shared publicly at the ARM Data Center and will provide powerful information for understanding and modeling how aerosols interact with deep convection systems within urban areas.